Evolution of magnetic energy (panel a), kinetic energy (panel b), instantaneous total heating (panel c), and total viscous heating (panel d) in the domain. Results are shown for resolutions 128² × 512 (blue), 256² × 512 (red), and 512² × 2048 (green). Magnetic energy is shown as a change from its initial, potential level. We remark that total and viscous heating are on different vertical scales.